The invention relates to a woodworking machine, such as a wood sanding machine, with a supporting and conveying device for an item during its passage through the machine, and with an endless belt which runs over two reversing rollers and is provided with a rib pattern on its upper surface for the formation of evenly distributed recesses, each of which has an air suction hole connected to the vacuum side of an air pump via channels, so that an item can be secured on the belt by the vacuum in the recesses during passage through the machine.
Machines of this type are used especially within the woodworking industry for various forms of finishing operations such as sanding.
Of such machines can be mentioned those for the sanding and polishing of surfaces in finishing operations, or as a link in a surface-treatment process such as lacquering.
For the feeding of the items during the processing in the machine, it is preferable to use an endless belt which is provided with holes and suction from underneath. This functions as a so-called vacuum conveyor on which the items can be secured.
With items having a limited plane supporting surface, the vacuum retaining power is naturally limited, the reason being that this depends solely on the area and thus the number of suction holes which the item can cover, and herewith the vacuum which exits under the item. In such cases, the retention is reduced, and thus the feed speed must be reduced in order to prevent the item from moving on the belt or possibly being lifted completely from the belt.
In such cases, the item must be secured manually to the belt by means of clamps, rails or the like. This is time-consuming and makes it difficult to effect an automatic working operation.